Participant/observation is useful as a tool for gathering evidence about processes, circumstances, or other observable conditions. A participant/observer is an investigator gathering evidence. Observations are carefully recorded, prejudgment is scorned, and judgments flow from the evidence. In approaching a situation to be investigated, the participant/observer should get a flavor of the system of which the situation is a part, identify those problems or parts of the system that influence the situation under investigation, and select the problems or parts that seem most important and might provide vital evidence. Once the situation is chosen, five types of data are often important: descriptive data about settings, accurate descriptions of actions and behaviors, word-for-word statements, traces and wear spots, and documents. The participant/observer is also interested in reliable witnesses and informants. Self-training exercises and sample observations are included. (Author/IRT)